This easter egg is found in the Season 1, Episode 9b titled, "Sand In Your Navel".

Description

In Season 1, Episode 9b of Rocko’s Modern Life when Spunky is being chased by a crab after he gets too close to the water the crab sees a “Crab Shack” and begins to run away yelling, “Oy, mi culito me pica!”.

While Google Translate says this phrase means, “Oy, my butt itches” (which is weird anyway) many people who natively speak Spanish have confirmed that culito is actually slang for “ass” which makes the final phrase, “Oy, my ass itches!”.